by Kastro CVE-2026-23455
Linux Linux — netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
Description · from the CVE record
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.
Affected
ProductAffectedFixed inSource
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < 2121f5fbe88daff0f1fc5bc47d359426c74b86b02121f5fbe88daff0f1fc5bc47d359426c74b86b0CNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < 65fa92f79677858b14b9e4b7275f26639afe271065fa92f79677858b14b9e4b7275f26639afe2710CNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < 495e97af9e7249ee02b72bb1d0848a6efc3700f4495e97af9e7249ee02b72bb1d0848a6efc3700f4CNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < f5e4f4e4cdb75ec36802059a94195a31f193da60f5e4f4e4cdb75ec36802059a94195a31f193da60CNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < 633e8f87dad32263f6a57dccdb873f042c062111633e8f87dad32263f6a57dccdb873f042c062111CNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < 9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df89d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8CNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < b652b05d51003ac074b912684f9ec7486231717bb652b05d51003ac074b912684f9ec7486231717bCNA
Linux5e35941d990123f155b02d5663e51a24f816b6f3 – < f173d0f4c0f689173f8cdac79991043a4a89bf66f173d0f4c0f689173f8cdac79991043a4a89bf66CNA
Linux2.6.17–CNA
SIMATIC S7-1500 CPU 1518-4 PN/DP MFPV3.1.6–siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFPV3.1.5–siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFPV3.1.7–siemens-SADP
Scores by source
Linux (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial